Accession Number : AD0722807

Title :   Advanced Research in Propagation Techniques.

Descriptive Note : Final rept. 20 Feb 70-19 Feb 71,

Corporate Author : STANFORD UNIV CALIF STANFORD ELECTRONICS LABS

Personal Author(s) : Waterman,Alan T. , Jr

Report Date : APR 1971

Pagination or Media Count : 19

Abstract : The report summarizes briefly the work performed under the subject contract on the use of a wave-front sampling antenna array in beyond-the-horizon propagation measurements. CW signals from a stable 3 GHz source are transmitted over a 102-mile transhorizon path. At the receiving site, an array of twelve spaced antenna elements is used to sample the arriving wave front. Amplitude and phase at each element are sampled in near simultaneity and stored on digital magnetic tape. The processed data are then presented in various forms: antenna scans in angle-of-arrival, doppler spectrum of the signal as received on one antenna element, doppler spectrum of the signal as received on the array of elements when phased so as to point in particular directions, distribution of signal level, and space correlation of the received signal. These processed data are then interpreted in terms of a flexible model of atmospheric structure. The model contains two component parts: a distributed turbulent structure which scatters the wave incoherently with a scattering cross section which varies inversely as some power of the scatter angle, and a stratified layer structure which reflects the wave coherently. The analysis permits a quantitative evaluation of the role played by these two processes. Meteorological measurements with an airborne microwave refractometer help confirm the interpretation. (Author)

Descriptors :   (*MICROWAVES, OVER THE HORIZON DETECTION), (*ANTENNA ARRAYS, MICROWAVES), PROPAGATION, DATA PROCESSING, SCATTERING, SCANNING, RADIOFREQUENCY, DOPPLER EFFECT

Subject Categories : Electrical and Electronic Equipment
      Radiofrequency Wave Propagation
      Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE